Valve-gear for pneumatic rock-drills.



No. 837,990. PATENTED M041, 1906.

G. WEIDMANN. VALVE G EA R FOR PNEUMATIC ROCK DRILLS.

APPLICATION FILED JUNE 17, 1 006.

2 SHEETS-SHEET 1.

zl/ z'zlzesses. 520612 for y Carl Widmarm PATENTED DEC. 11, 1906.

0. WEIDMANN; VALVE GEAR FOR PNEUMATIC ROCK DRILLS APPLICATION FILED JUNE 17, 1906.

2 sums-sum 2.

Fi A.

UNITED STATES PATENT OFFICE.

CARL WEIDMAIVN, OF WIIRSELEN, GERMANY, ASSIGNOR OF ONE-HALF TO PAUL HOFFMAN, OF EISERFELD. NEAR SIEGEN, WESTPHALIA,

' G ERMANY.

Specification of Letters I'atent.

Patented Dec. 11, 1906.

Application filed June 17,1905- Serial No. 265,649.

To all whom it may concern.- v

Be it known that I, CARL WEIDMANN, en-

gineer and assistant in the Royal Polytechothers skilled in the art to which it appertains to make and use the same.

It is a well-known fact that pneumatic rock-drills which in the absence of an especial distributing-valve are governed by the drill-operating piston itself labor under the great disadvantage that their stroke is a very limited one. Other rock-drills which are solely governed by an automatically-moved distributin -valve show this disadvanta e, that the va ve-gear is not trustworthy, as t e smallest retardation of the valve caused by dirt and the like may cause the drill-operating piston to strike the head of itslcylinder.

My present invention represents a combination of these two different ways of 'overning a rock drill; and its object is to o away,

with the disadvantages enumerated above. To this end the operation of the rock-drill is governed at the rear end of the cylinder, first,

y the drill operating piston itself and then by the aid of an auxiliary distributing-valve,

whichcontrols'the admission during the ad-.

vance stroke and the exhaust during the .back stroke to obtaina stroke of any desired len th'. At the front end of the cylinder the dril -operating piston is solely governed: by means of the auxiliary distributingevalve.

The new valve-gear ma as profitably be applied to all other kinds of pneumatic tools with a reciprocating motion as it is to rockdrills. I. In the accompanying-drawn s, Figures 1,

- 2,3, and iare vertical longitu inal sections of a rock-drill cylinder and show the drill-opera'tfiig piston and the auxiliary distributingvalve in difierent relations to [each other. Fi 5 is a cross-sectional view on the line 515 ofI i 1. Fi'g.'6 is a similar view on the line 6 6 0 Fig. 1. j

In the cylinder 1 the drill-operating piston 2 is, arranged and provided with a piston-rod 3, as usual. This rod is guided in the neck 4 of the cylinder 1 and carries at its free end a drill. (Not shown.) The rear end of the cylinder 1 is closed bya cylinder-head 5. In the valve-casing 6, here supposed to form an inte al part of the cylinder 1, the stepped auxi 'ary distributing-valve 7 is arranged, and the openings arranged opposite the ends of said valve are closed by the screw-plugs 8 and '9. The distributing-valve 7 is provided with the annular recesses 10 and 1 1.

The compressed air is admitted into the casing 6 through the inlet-pipe 12, passes through the passage 13", and comes into contact with the surface 14 of the smaller end of the auxiliary distributing-valve 7. In this manner this end of said valve is always kept under ressure. By means of the port 15 the su ace 16 of the larger end of said auxiliary distributing-valve 7 is always kept in communication with cylinder-space 17 at the rear end of the piston 2. The inlet-port 18is at all times connected with the inlet-pipe 12 By the aid of the circumferential .holes 22 and the longitudinal central bore or recess 23 the ports 18, 19, and 21 can be alternately,

brought into communication with the cylin-' der space 17. Through the instrumentality of the valve 7 the port 25, communicating with the cylinder-space 24 in front of the pi: I ton 2,1is alternately brought into communication with the exhaust-port 19 and with the passage 13. i

The operation of the new valve-gear may now be eiiplained with regard to-the Figs. 1, 2, 3,1111 4..

In Fig. 1 the drill-operating piston 2 is moving backward under the influence of the "pressure which exists in the cylinder-space 24. The circumferential holes 22 of the pis'-- ton have just commenced to uncover the inlet-port 187st that the cylinder-space 17 at -upon the surface 16 the cylinder-space 24. '1' how the annular recess 11 connects the rear of the iston 2 is supplied with compressed air an the direction of travel of the piston 2 reversed. At tihe same time pressure is exerted upon' the larger surface 16 of the valve 7 by way of the ort 15, and thus the valve 7 compelled to taiie up the position shown in Fig. 2, since the surface 16 is larger. thanthe surface 14. Fig. 2 shows that in this position of the auxiliary distributingvalve 7 the annular recess connects the port 21 with the inlet-port 18 in such a manner that when the circumferential holes 22 are situated in front of the port 21 during the advance stroke of the iston 2a second admission, the so-called auxiliary admission, of compressedair into the cylinder-space 17 takes place. At the same time the valve 7 brings the port 25 and the cylinder-space 24, connected therewith, in communication with the exhaust-port 19 and wit-h the exhaust-opening 20 by means of the annular recess 11, and thus permits the piston 2 to further advance under the pressure existing in the cylinder-space 17.

In Fig. 3 is shown how during the advance of the piston 2 the circumferential holes 22 commence to uncover the exhaust-port 19, through which the compressed air which fills the cylinder-space 17 now may enter the exhaust-opening 20 and escape. SimultaneT ously herewith the compressed air; acting of the valve 7, escapes through the port 15, so that the pressure acting upon the smaller surface 14 of the valve 7 can movethe latter into the position shown in Fig. 4, during which operation the piston 2 accomplishes the blow.

. Fig. 4 shows how during the time the valve 7' remains in the position indicated therein the port 25 and thei'cy'linder-space 24 keep up communication with. the passage 13 and with the inletpipe 12 and how the piston 2 is driven back again by the pressure existing in Fig. 4 further shows the port 21 with the exhaust-port 19 and with the exhaust-opening 20, so that when the circumferential holes 22 of the piston 2 commence to uncover the port 21 during the back stroke of the iston 2 another exhaust, the so-called auxi iary exhaust, from the cylinderspace 17, takes place. When during the furt er advanced back stroke of the piston 2' the circumferential holes 22 again'begin to un. cover the admission-port 18, the cycle of operations described above begins anew.

To vouchsafe a correct working of the valve-gear without any loss of compressed air, the distance between the ports 18 and 21, on the one hand, andbetween the latter and the port 19, on the other hand, must be greater than the length of the holes 22 in the circumference of the piston 2, so that these holes cannot communicate with two of these ports at the same time.

Though considering the present arrangeinent 0 parts as the most advantageous, minor changes in the details of constructiofis and arrangement of'parts may be resorted to without departing from the spirit of my' invention. I

-1. In a valve gear. for pneumatic rockdrills, the combination with a cylinder, of a valve-casing, a stepped auxiliary distributing valve with -annular external recesses,

an inlet-port constantly communicating with one of said recesses, an exhaust-port constantly-communicating with theother of said recesses, an auxiliary port communicating with the inlet-port when said valve is placed in one end position and with said exhaustport when said valve is placed in the other end position, a drill-operating piston reciprocating in said cylinder, a'longitudinal open recess in said piston, and circumferential holes in said piston communicating alternately with said port, and said exhaust port and always through said recess in communication with the cylinder-space communicating withthe means of the latter and said auxiliary port the admission of air to the rear end'of said piston during the advance stroke after the inlet-port has been covered by said piston and by the same means keep the exhaust from the rear end of said cylinder open during the back stroke after the exhaust-port has been covered by said piston.

- .2. A valve-gearfor pneumatic rock-drills comprising acylinder, a valve casing, a stepped auxiliary distributing valve with annular external recesses, an air-inlet always communicating with the smaller end surface of said valve, a port communicating with the larger end surface of said valve and with the rear end of said cylinder, an inlet-port constantly communicatingvwith one\of' said recesses, an exhaust-port always in communiiliary port situated between said inlet-port and said exhaust-port and communicating with the inlet-port when said valve is place in one endposition and with the exhaustport when said valve is placed in the other end position, longitudinal open recess therein, circumfe'rential holes in said piston communicating alternately auxiliary port and said exhaust-port and always through said recess'in communication with the rear end of said cylinderto maintain the admission of aii to the rear end of said cylinder during the advance stroke by -means of said valve and'said auxiliary port after the inlet-port has been covered by said iston and'by the same. means keep the exhaust from the rear end of said cylinder open during the back strokeafter the exhaustwith said inlet-port, said inlet-port, said auxiliary i larger end surface ofsaid valve to permit by cation with the other of said recesses, an aux a ilrill-operatihg piston, a

port has been covered by said piston, an eX- In testimony whereof I have signed my haust-opening communicatiniwiththe valvename to this specification in the presence of 10 bore, and a portconnecting t e front end of two subscribing witnesses.

said cylinder with said Valve-bore and communicating with said air-inlet when said valve is placed in one end position and com- Witnesses: Inunicating with the exhaust-opening when HENRY QUADJLIEG said valve is placed in the other end position. E. M. l31wrnmcm.

CARL WEIDMANN. 

